DESCRIPTION

The
netgroup
is a SunOS invention.
A netgroup database is a list of string triples
(hostname, username, domainname)
or other netgroup names.
Any of the elements in a triple can be empty,
which means that anything matches.
The functions described here allow access to the netgroup databases.
The file
/etc/nsswitch.conf
defines what database is searched.

The
setnetgrent()
call defines the netgroup that will be searched by subsequent
getnetgrent()
calls.
The
getnetgrent()
function retrieves the next netgroup entry, and returns pointers in
host,
user,
domain.
A null pointer means that the corresponding entry matches any string.
The pointers are valid only as long as there is no call to other
netgroup-related functions.
To avoid this problem you can use the GNU function
getnetgrent_r()
that stores the strings in the supplied buffer.
To free all allocated buffers use
endnetgrent().

In most cases you want to check only if the triplet
(hostname, username, domainname)
is a member of a netgroup.
The function
innetgr()
can be used for this without calling the above three functions.
Again, a null pointer is a wildcard and matches any string.
The function is thread-safe.

RETURN VALUE

These functions return 1 on success and 0 for failure.

FILES

/etc/netgroup/etc/nsswitch.conf

ATTRIBUTES

For an explanation of the terms used in this section, see
attributes(7).

Interface

Attribute

Value

setnetgrent(),
getnetgrent_r(),
innetgr()

Thread safety

MT-Unsafe race:netgrent
locale

endnetgrent()

Thread safety

MT-Unsafe race:netgrent

getnetgrent()

Thread safety

MT-Unsafe race:netgrent
race:netgrentbuf locale

In the above table,
netgrent
in
race:netgrent
signifies that if any of the functions
setnetgrent(),
getnetgrent_r(),
innetgr(),
getnetgrent(),
or
endnetgrent()
are used in parallel in different threads of a program,
then data races could occur.

CONFORMING TO

These functions are not in POSIX.1, but
setnetgrent(),
endnetgrent(),
getnetgrent(),
and
innetgr()
are available on most UNIX systems.
getnetgrent_r()
is not widely available on other systems.

NOTES

In the BSD implementation,
setnetgrent()
returns void.

SEE ALSO

COLOPHON

This page is part of release 4.13 of the Linux
man-pages
project.
A description of the project,
information about reporting bugs,
and the latest version of this page,
can be found at
https://www.kernel.org/doc/man-pages/.